In September 2011, the European Commission decided that new cars need to be equipped with an automatic emergency system which self-actingly informs a rescue coordination center in the case of a traffic accident as from the year 2015. In the case Of an accident, the severity of the accident is to be detected via crash sensors. The result is supposed to be transmitted to an emergency call center via a mobile radio communication network together with other data, for example, the location of the accident (which can be determined e.g. via Global Positioning System (GPS)), which center thereupon immediately informs the responsible rescue coordination center. Hopes are that the number of traffic deaths may be significantly reduced through rescue measures which can be initiated more rapidly as a consequence thereof.
As generally known, the term “on-board power supply system” of a motor vehicle refers to the entirety of all the electric components therein. Generally, it comprises an energy storage device from which it is supplied, where required an electric generator, sensors, modules for position determination (e.g. a OPS module), indicator elements such as warning lights and control lights, actuators (in particular electric motors), audio systems (speakers, audio amplifiers) as well as one or more control devices that actuate the components, in particular an on-board electronic system, and cable systems and bus systems connecting the aforementioned.
In the case of accidents, the on-board power supply systems of the motor vehicles involved in the accident are often affected or even intentionally deactivated. Therefore, an emergency system generally comprises a distinct energy storage device, a back-up battery or emergency battery, and is therefore independent from the energy storage device that supplies the on-board power supply system.
As generally known, the capacity of batteries depends on the operating temperature to a significant degree. At low temperatures, for example, at temperatures of less than 0° C. which can typically occur during a European winter, commercially available battery systems provide significantly lower voltages than at temperatures above 0° C. Their capacity decreases to a fraction of the nominal capacity. To ensure the functioning of an emergency system even in such extreme situations, it is common to dimension battery systems significantly greater than would be necessary for an operation exclusively at “normal temperature” (e.g. at an outdoor temperature between 0° C. and 40° C.)
There is, therefore, a need to provide an emergency system which performs its functions reliably even at extremely low temperatures.